Author: Ragstaff (nme-pow-pr3.tpgi.com.au)
Date: 04-19-2004 16:00
My idea did move on a little from the initial thoughts (which was basically what you describe now), but they come at the risk of making the upgrade more expensive and complicated. It could also make it simpler in some aspects, by meeting the requirement for an IDE controller, an ethernet port, and possibly a graphics card.
It smacks of "scope creep" though, so take it with a grain of salt. You're board would be wonderful to see in action! I've had these ideas swimming around in my head for a year though, and they do appeal to me...
The two main ideas are:
1) Have a socket for the DSP56L307 instead of the maths co-pro. Ok, sounds crazy, but the things is, these are CHEAPER than a 32mhz 68882 from Motorola and would give so much more power (290 mips @ 160mhz, only 1.8volts).
Motorola have taken the price off the site now (http://e-www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56L307&nodeId=03z6wYqRXz8596), but I clearly remember these chips costing less than $20USD.
There is hardly any ST software that has been written to use the a maths co-pro, so it's not like "oh we'd have to re-write everything to work with the DSP".
What DOES exist is a lot of 56k DSP routines and knowledge in the Atari community thanks to the Falcon. All I'll say is "hmmm" :-)
I'm sure some smart person in the future could write an 881/882 emulator that runs on the DSP, so that it appears as a maths co-pro to the ST anyway. I'm not saying it would be easy...
Perhaps with the socket you place on the board, you would need to allow the DSP to be memory-mapped to the same address as the maths co-pro, so that when the 68882 emulator is running on the DSP, "old" ST code that uses a maths co-pro would be able to run.
There's also the cheaper DSP56367, but it only has 20k of ram:
"150 MIPS with a 150 MHz clock at 1.8 V core with a 3.3 V peripheral I/O OR 100 MIPS with a 100 MHz clock at 1.5 V core with a 3.3 V peripheral I/O
Object Code Compatible with the 56 K core "
Available from $9.50USD to $15.85USD
2) Dragonball MC68SZ328 for $8.98USD. This is a micro-controller with a 68000 @ 66mhz, on-board USB1.1 controller, "TFT colour LCD", DMA controller, A/D converter (16 12-bit channels), amongst other things.
I have looked at some doco, and this is the important thing: the chip-selects *ARE* programmable. This means AFAIK that when the micro-controller boots, you can move all of the on-board peripherals to anywhere in memory with software, so there would be no need for them to conflict with ST hardware/peripherals. So, we have in effect a 66mhz 68000.
And what of the USB 1.1 controller? There is a whole lot of code on the motorola site pre-written for using the port, so that's a help...
I realise we can't use USB peripherals without writing drivers for them, which would be a lot of work, but 2 things I think would be worth investing the effort in are:
- Drivers for a USB memory stick. This could remove the requirement for an onboard IDE controller, because we could just plug a cheap 64mb or 128mb memory stick in for all the mass-storage an ST could need.
Imagine how easy it would be to transfer data from the ST to the PC and Mac as well...
- Driver for one of these ethernet -> USB adaptors. If you can get that working, you don't need to put ethernet on the board.
Of course, if the programmable chip-selects don't work as I believe they do, then this whole idea is hopeless.
One more thought: If people can put their own oscillators on this board, they can overclock these chips even further. With the dragonball, I have heard this really messes with the LCD controller (timing dependancies), and I imagine the USB and DMA controllers would suffer in the same way...
While the LCD driver opens up the possibility of new graphic modes (so this thing is a grafics card as well!), maybe we would just ignore it, as everything would need to be totally re-written to use it...
The dragonball and the DSP56367 would cost the user < $20USD all up, or ~$30USD for the dragonball + DSP56L307.
Not too expensive for an ST upgrade? But the design could be quite expensive, I realise....
Oh, one laassstt thought.
Memory is so cheap per mb now. The 68000 can only address 16mb. I'm sure you could get a 16mb chip from some manufacturer for a few $ these days. I wonder if this board could have a slot for that? It may be proprietry and very small...
|
